Effect on South American CL: This proposal would lump two species currently
recognized as separate species on our baseline list.

Background: For most of their history, taczanowskii and nigrofumosus have
been recognized as sister taxa. They are allopatric (nearly parapatric) taxa
with no known contact zone; taczanowskii is endemic to coastal
Peru, and nigrofumosus, endemic to coastal Chile. No data published data
exist on characters directly relevant to assessing potential interbreeding such
as vocalizations. They are (presumably) 100% diagnosable phenotypic units based
on plumage characters. The primary differences in plumage are (apparent) degree
of pigment saturation, with taczanowskii paler overall. The only
pattern differences are not "quantum" but a matter of degree: less
conspicuous superciliary and reduced breast spotting in taczanowskii.
(If the Peruvian coastal environment were "paler" overall than that
of Chile, then this would be an example of Gloger's Rule variation.)

Cory
& Hellmayr (1925) considered these two taxa as separate species, but noted
that taczanowskii was "probably a northern race of nigrofumosus".
Peters (1951) maintained them as separate species (somewhat surprising giving
the several novel lumps of species-level taxa in that treatment). Meyer de
Schauensee (1966, 1970) considered them conspecific, without providing any
rationale. Vaurie (1980) and Sibley & Monroe (1990) treated them as
separate species. Ridgely & Tudor (1994) also considered them as separate
species and noted that their ranges are allopatric by no more than 70 km, and
noted that no signs of intergradation have been detected. Remsen (2003)
maintained them as separate species but noted that evidence for this is weak,
but no worse than for species-level treatment of several other taxa in Cinclodes (e.g., C. aricomae, C.
olrogi, and C. comechingonus).

Analysis: This problem is like perhaps several hundred others in South
America with respect to species-ranking of allopatric sister taxa: we don't
have enough data to make a sound decision one way or another, but we need to
deal with them. It would be reasonably easy to obtain vocal data on these and other
Cinclodes to do an analysis following the protocols established by
Isler, Isler, & Whitney (1998), but that's for the future. The plumage
differences are not really much more than that shown among several subspecies
of C. fuscus, but they are also of the same magnitude as those
among the taxa ranked as species noted above.

Recommendation: I will vote "NO" on this proposal because in the
absence of data, I see no reason to change our current classification, which
uses narrowly defined species limits in Cinclodes. Perhaps when we
have real data on one or two of these "borderline" cases, we can
apply those results to this one if no more direct data become available in the
meantime.

SIBLEY, C. G., AND B. L.
MONROE, JR. 1990. Distribution and taxonomy of birds of the World. Yale
University Press, New Haven, Connecticut.

VAURIE, C. 1980.
Taxonomy and geographical distribution of the Furnariidae (Aves,
Passeriformes). Bulletin of the American Museum of Natural History 166: 1-357.

Van Remsen, July 2003

P.S.:
If the proposal does not pass, then I'll work on another one on the English
names of these two.

===========================

Comments from Schulenberg: "My vote: "No". I haven't seen
a taczanowskii in the flesh in a while now, and we don't have
many specimens of it. But in addition to being paler and less spotted below, I
thought that it had a "dingy" throat. Nigrofumosus, on the
other hand, has a very white throat contrasting with the darker body. I'm impressed
that two such different looking taxa so closely approach one another without
(known) introgression. That said, earlier this year Alvaro Jaramillo saw a bird
in northern Chile that threw him: it either was a taczanowskii (which
would be a new record for Chile) or was something intermediate. Of course, n =
1 for intermediates or hybrids does not make much of a case for lumping either.
But I'll be interested to see Alvaro's comments on this proposal. "

Comments from Robbins: "NO, mostly as a result of historical
treatment; obviously we need vocalizations of these two taxa to really
understand what is going on."

Comments from Stotz: "I vote to keep the two Cinclodes
separate, although the evidence is weak, based on close approach without
intergradation. Status quo helps here too."

Comments from Zimmer: "I vote "no" on proposal to
lump Cinclodes taczanowskii and C. nigrofumosus,
primarily on the basis that there is no published rationale to support the
change. Tom's points concerning the close approach without apparent
intergradation, and the distinction in throat color are also well-taken."

Comments from Stiles: "NO (until evidence is published)."

Comments from Silva: "We need more evidence to make this
change."

Comments from Jaramillo: "NO. There certainly is a need to compare
vocalizations of these two Cinclodes, and all Cinclodes for
that matter. I had thought that a couple of birds I saw in Arica, northernmost
Chile were taczanowskii-like while in the field. After looking at photos
of taczanowskii, I haven't been able to see skins recently, it was clear
to me that the birds I saw were nigrofumosus, and not intermediate at
all. The Arica birds may be a little paler on the upperparts and underparts
than more southern nigrofumosus, but in other features do not
resemble taczanowskii at all. The Arica birds had bold and
bright white throats, and supercilia, as well as cinnamon wing stripes. Skins
and photos of taczanowskii I have seen show pale buff wing
stripes, buffy or brownish supercilia, and no clear white throat patch. There
are also differences in tail pattern, and distinctness of underpart streaking,
the bold streaking of the Arica birds is consistent with nigrofumosus again,
not taczanowskii. So in terms of physical appearance, perhaps there is a
cline within nigrofumosus, with northern birds being paler than
southern birds, but so far no sign of intermediate populations between nigrofumosus
and taczanowskii. In fact, the white supercilia of the Arica birds was
more extensive than on more southern nigrofumosus, so in this feature
alone the northern Chilean birds are actually less like the nearby taczanowskii than
expected due to geographic proximity. Keep in mind that these observations are
based on a pair of birds only. Individuals of nigrofumosus I have
seen in Iquique a bit to the south did not strike me as anything other than
pretty typical nigrofumosus. In conclusion, my field observations from
Arica don't suggest there is an intermediate population here. Arica is a key
site as it is where the northernmost rocky habitat is found in Chile, and both
of these Cinclodes are restricted to rocky coastal habitats.
North of Arica there are many, many miles of sand beaches without rocky
outcroppings. I think it is at least 40 km or more of beach, and this is
certainly the ecological separation between these two taxa. It would be
interesting to study skins, if they exist, of the southernmost Peruvian
population. My guess is that there will be no tendency towards intermediacy. As
such, I am comfortable retaining these two taxa as separate species until
intermediates are found, or vocal or molecular data suggests otherwise. Note
that plumage differences between many good species in Cinclodes (sympatric ones like oustaleti, C. fuscus
fuscus, patagonicus, or C. fuscus albiventris and atacamensis)
are slight to moderate. In many cases they are less distinct than the plumage
differences between taczanowskii and nigrofumosus.
I think that this is a more valid comparison than comparing to differences in
plumage within fuscus, as almost surely those well-marked subspecies are
good species. I have been slowly collecting recordings of C. fuscus fuscus,
and C. fuscus albiventris. An even more limited data set I have suggests
that northernmost albidiventris is another diagnosable group, based on
vocalizations. That is a proposal for the future, when I have more data."